“Nature Is Inexorable and Immutable; She Never Transgresses the Laws Imposed Upon Her, Or Cares a Whit Whether Her Abstruse Re
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“Nature is inexorable and immutable; she never transgresses the laws imposed upon her, or cares a whit whether her abstruse reasons and methods of operation are understandable to men” Galileo Galilei (1564 – 1642) “As my father’s daughter, I felt I had a duty to get involved” Aung San Suu Kyi (1945 - ) University of Alberta Yolk Sac Infections in Broiler Chicks: Studies on Escherichia coli, Chick Acquired Immunity, and Barn Microbiology by Ana Milena Ulmer Franco A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Animal Science Department of Agricultural, Food and Nutritional Science ©Ana Milena Ulmer Franco Fall 2011 Edmonton, Alberta Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission. To God, the Almighty Father To my beloved husband Lance, for his unlimited support at all times To my Colombian and Canadian families, for believing in me Abstract The avian yolk sac is a well vascularised membrane that surrounds the yolk of an embryonated egg and functions as a placenta-like structure transferring yolk nutrients including maternal antibodies, to the embryo. The absorption of the yolk sac content during the first days post-hatching is essential for chick growth and development. However, the infection of the yolk sac is the main cause of chick mortality accounting for large economic losses to the poultry industry. The overall goal of this thesis was to study the epidemiological triad of yolk sac infections: the pathogen: Escherichia coli, the susceptible host: the chick, and the environment: the chicken barn. In the first experiment a strain of avian pathogenic E. coli was transformed with a plasmid carrying a green fluorescent protein. Using fluorescence microscopy it was observed that E. coli entered the yolk sac via the chick navel. In the second experiment, the effects of breeder flock age on the total IgY content of egg yolk and yolk sac was determined. It was concluded that IgY increased with breeder flock age in eggs and yolk sacs. The consequences of these results on chick health are unknown. In the third experiment, the effects of cleaning and disinfection methods of the chicken barn on microbial counts were analyzed in barn swabs and in pooled organ and yolk sac samples. It was surprising to observe that 4 days after placing chicks in the barn, samples of chicks from “cleaner” pens had more bacteria than those of chicks from “dirtier” pens. In the fourth experiment, all E. coli isolated from barn and chick samples from the previous experiment were typified using the RAPD method. It was determined that “cleaner” pens had greater E. coli variability than “dirtier” pens. Also, more E. coli types were shared between chicks and the environment in “cleaner” pens suggesting that chicks that are placed in very clean environments acquired more environmental E. coli than chicks placed in environments with greater bacterial loads. The long term consequences of environmental sanitation on chick growth and development, disease susceptibility, and broiler performance should be studied. Acknowledgements At the end of the tortuous and thorny road, this doctoral thesis will only have one author. However, this project could have never been completed without the support, help, advice, and experience of several people and institutions. I hope no one is left behind in this list. I am most especially grateful to my beloved husband Lance, for his support throughout this arduous and sometimes frustrating process. First and foremost: to my supervisor, Dr. Lynn McMullen, for “adopting” me and my project into her research team, and for supporting me at all times. To my parents Luis Eduardo and Elida, for nurturing my love for learning, for respecting my decisions (the good and the bad) and for believing in me. To my abuelita (grandma) Carmen, the wisest and most loving woman. I miss you all. To Dr. Gaylene Fasenko, for giving me the opportunity to enter this path. To my doctoral committee members, Drs. Leluo Guan and Jianping Wu, for their assistance and recommendations. To Dr. Kathy Magor, for introducing me to the fascinating world of avian immunology and for her unconditional and constant advice. To the University of Alberta Poultry Research Centre staff for their co-operation with barn and hatchery duties. To the former incubation research group at the University of Alberta: Erin Christopher, Jacob Hamidu, Margaret MacKenzie, Thania Moraes and Josue Romao, for all their help during sample collection. To the Biological Sciences Animal Facility staff at the University of Alberta, especially to Simmone Kerswell, for their careful management of chicks. To the Biological Sciences Advanced Microscopy Unit, especially to Arlene Oatway, Randy Mandryk and Dr. Rakesh Bhatnagar, for their assistance with sample preparation for fluorescence microscopy. To Dr. Gita Cherian and Ms. Nathalie Quezada, from Oregon State University, for their training and assistance with IgY determination. To the AFNS Food Microbiology lab members, for their guidance and their help during sample processing (special thanks to Brenna Black, Elena Dluskaya, Melissa Haveroen, Christine Liu, Aaron Pleitner, Kathleen Vail, Heather Vandertol-Vanier, and Patrick Ward). To Emma Hernandez-Sanabria for her coaching with molecular techniques and statistical analysis of bacteria. The financial support for this research was provided by the Alberta Livestock and Meat Agency, the Natural Sciences and Engineering Research Council of Canada, and the Saskatchewan Chicken Industry Development Fund. The donation of broiler chicks from Maple Leaf Hatchery is always appreciated. On a personal note, I‟d like to thank Dr. Francisco Henao (Professor, Universidad de Caldas, Colombia), Dr. Alberto Botero (Scientific Manager Avidesa Mac Pollo, Colombia), and Dr. Juan Carlos Rodriguez-Lecompte (Assistant Professor, University of Manitoba) for being mentors at different stages of my life. Your support encouraged me to pursue this dream. Life would not be the same without the company of our furry family: Argos, Havoc (alias Monkey) and Leo, our hiking partners, and Split and Sparta, our purring lap warmers. Table of Contents 1. Introduction and Literature Review: Avian Pathogenic Escherichia coli (APEC) __________________________________________________ 1 1.1. Introduction _________________________________________________ 1 1.2. History _____________________________________________________ 2 1.3. Classification ________________________________________________ 3 1.4. Biochemical Properties ________________________________________ 4 1.5. Growth Requirements and Colony Morphology __________________ 5 1.6. Serological Characteristics of E. coli _____________________________ 7 1.6.1. Somatic Antigens _______________________________________ 7 1.6.2. Protein Antigens ________________________________________ 9 1.7. E. coli virulence factors _______________________________________ 10 1.8. Strain classification __________________________________________ 13 1.9. E. coli infections in humans ___________________________________ 15 1.10. E. coli infections in domestic animals __________________________ 19 1.11. E. coli infections in poultry ___________________________________ 21 1.11.1 Omphalitis / yolk sac infections __________________________23 1.11.2. Reservoirs of avian pathogenic E. coli _____________________25 1.11.3. Virulence factors of avian pathogenic E. coli _______________26 1.11.4. Protection of chicks against E. coli infections ______________ 28 1.12. APEC: a new foodborne pathogen? ___________________________ 31 1.13. Economic Impact of APEC Infections _________________________ 35 1.14. Conclusion ________________________________________________ 37 1.15. References _________________________________________________ 39 2. The Use of peGFP Escherichia coli to Establish that Yolk Sac Infection Occurs Via the Broiler Chick Navel ____________________________ 55 2-1. Introduction ________________________________________________ 55 2.2. Materials and Methods _______________________________________ 57 2.2.1. Preparation of peGFP-tagged avian pathogenic E. coli _______ 58 2.2.2. Chick collection and infection ____________________________ 61 2.2.3. Tissue collection and processing __________________________ 64 2.2.4. Slide analysis __________________________________________ 66 2.2.5. Statistical analysis ______________________________________ 67 2.3. Results _____________________________________________________ 68 2.4. Discussion _________________________________________________ 76 2.5. Conclusion _________________________________________________ 81 2.6. References __________________________________________________ 82 3. Hatching Egg Yolk and Newly Hatched Chick Yolk Sac Total IgY Content at Three Broiler Breeder Flock Ages ___________________ 89 3.1. Introduction ________________________________________________